Multimode VoIP terminals can roam on a number of wired or wireless access technologies by way of a common gateway such as a residential gateway. Because of the nomadic nature of multimode VoIP terminals, it can be difficult to know when said terminals are roaming outside of a home network (e.g., a residence or commercial enterprise) since what is generally known about the terminal is its IP address which is not fixed to a single location. It is similarly a challenge to locate the VoIP terminal once it has roamed outside of its home network.
These complications can make call processing problematic for service providers especially in situations where the caller is attempting to communicate with an emergency response center such as a public service access point (PSAP) for 911 services which requires knowledge of the terminal's location to comply with Federal Communications Commission (FCC) regulations.
A need therefore arises for a method and apparatus for processing SIP messages associated with a VoIP terminal.